Loser: Grounded

No happy landings for latest twist on sci-fi staple

When is a flying car not a flying car? When it’s a Transition and when its maker, Terrafugia, insists on calling it a ”roadable aircraft.”

Think of it as an airplane prototype suited for limited operation on land, the Cambridge, Mass., company says. In other words, do your best to imagine an eccentric flying machine that only occasionally moonlights as a car.

Like platform shoes and plastic flamingos, the convertible car–airplane concept just won’t go away. During the past century, dozens of models have emerged, including one capable of vertical takeoff and one with bolted-on wings that pilots detached and carted along in a trailer. None have risen above the status of historical footnote.

Here’s the problem: it has proven to be virtually impossible to craft a light, agile plane that also handles well on the road. Basically, a car is safer and more stable when it’s heavier, while a plane flies better when it’s lightweight.

So far, Terrafugia has completed a detailed design and is now trying to raise funds to build a prototype by 2008. To hide the fact that the Transition is a flimsy car and a feeble plane, Terrafugia designed the vehicle to weigh just under 600 kilograms, the cutoff for the U.S. Federal Aviation Administration’s new light-sport aircraft class. Such planes are to be flown only in good weather at low altitudes and relatively slow speeds, and Terrafugia hopes that in this class, the Transition’s limitations won’t stand out.

In Terrafugia’s simulations, the Transition looks like a stubby little plane affixed to a four-wheel platform. At the push of a button, the wings fold and tuck in alongside the body, sort of like the wings of a perched eagle. With bumpers on both ends, the car-shaped body would cause the Transition to experience more drag and fly at slightly lower speeds than other light-sport aircraft. Unlike those on normal planes, its wings would be flat on the bottom so that they could fold completely—which reduces the Transition’s aerodynamic performance.

What the Experts Say

GORDON BELL: If he builds one, it may be good training. No harm done. Every decade, someone should try to build one.

As a car, however, the Transition fares far worse. Although 600 kg isn’t unreasonable for a light prop plane, it is decidedly wispy for a car. For comparison, a Mini Cooper, one of the smallest four-seat cars that is widely available in North America, weighs almost twice that much. A strong gust of wind could cause the Transition to fishtail. To make things worse, its folded wings would create mammoth blind spots on a vehicle the length of a large pickup truck and would be easy targets for fender benders.

Terrafugia says that in car mode, the Transition would typically be used only to drive between home and airport. Still, that might be enough to exasperate its owners. ”We have become very demanding when it comes to safety issues in cars,” says C.P. (”Case”) van Dam, a professor of mechanical and aeronautical engineering at the University of California at Davis. ”We expect comfort and high performance.” The same expectations have shaped pilots’ preferences in small aircraft, van Dam notes, adding, ”If you end up compromising in both areas, do you really satisfy a large enough group of people?”

Amateur pilots buy approximately 1000 small aircraft each year, according to Richard Golaszewski, executive vice president of GRA, an aviation consultancy in Jenkintown, Pa. Carl Dietrich, Terrafugia’s chief executive, estimates that the market is slightly larger and says he is confident he will sell ”a couple hundred” Transitions annually in each of the next few years—which would be quite an accomplishment for an unknown, untested design team.

Priced at US $148 000, the Transition falls significantly outside the $50 000 to $100 000 price range of new light-sport aircraft. By opting for an $80 000 Rans S7, for example, a pilot could, for the same amount of money, choose to spend the remaining $68 000 on cab rides, rentals, or a new superloaded Chevy Corvette.

Dietrich, who is working on a Ph.D. in aeronautics and astronautics at MIT, won the 2006 Lemelson-MIT Student Prize for the Transition’s design. Using the $30 000 award, Dietrich launched Terrafugia that spring, with the hope that his vehicle would make noncommercial air travel significantly easier.

Dietrich is not alone in his belief that the airspace over the world’s sprawling metropolises is clogged, with little room for growth. Many say that regional airports provide a convenient outlet and that the main obstacle impeding their use is the trouble of getting a pilot to and from the airport. According to Dietrich, only one third of the 5000 general-aviation airports in the United States have taxi or car-rental facilities nearby. With the Transition, Terrafugia’s engineers dream that personal air travel will finally become mainstream. ”Comparing two different light-sport aircraft, one standard and the Transition, there’s a lot of draw to an airplane you can keep in your garage,” Dietrich says.

Even if Terrafugia meets its goals, the air expressways of Back to the Future and ”The Jetsons” will remain the stuff of daydreams. Boeing and NASA have independently analyzed the feasibility of personal air vehicles and each concluded that a wider problem hinders individual air travel: the absence of support structures to make increased traffic safe and reliable.

”After an initial look at designing a vehicle, we decided we were missing the big picture,” says Lynne Wenberg, a senior manager at Boeing’s Phantom Works research division in Seattle. More traffic at small airports necessitates more air traffic management, control towers, and systems to help lower-skilled pilots land in bad weather. NASA aviation expert Bruce Holmes argues that small airports would have to undergo a ­massive, ­government-supported update. ”This is really not going to be a one-company development,” Holmes says.

At the moment, however, the U.S. National Highway Traffic Safety Administration holds sway over Terrafugia’s future. If the agency decides the Transition is sufficiently carlike, Terrafugia will have to comply with crashworthiness standards that would add weight to the car and further complicate the design, potentially dooming it.

Rather than abandon the light-sport aircraft idea, Dietrich says he would resort to a three-wheeled version, to be classified as a motorcycle, which has looser safety requirements. Some aircraft designers, including NASA’s Holmes, actually prefer the idea of a flying tricycle, because it is less likely to become mired in traffic safety restrictions. But Dietrich is reluctant to move in that direction, hoping to keep the vehicle in a more familiar shape.

For the time being, the flying car stays tethered to the shop, a clunky compromise whose time may never come.